Completions can involve insertion of section of screen in an isolated zone that is sealed off with packers. The screen assembly is sealed into the lower packer and generally has a section of blank pipe above the screen portion connected to the bottom of the upper packer at either end of the zone that is isolated for subsequent production. When the completion plan calls for fracturing and gravel packing the procedure is to deliver the proppant in viscous slurry through the top packer. From there the slurry goes through a crossover to get into the annular space around the screen. As long as some portion of the screen is uncovered the pressure of the viscous carrier fluid can be communicated to the formation in a fairly predictable manner. Once the annular space fills high enough with proppant to cover the screens, the pressure can rise rapidly. This is because the annularly shaped pile of proppant in viscous fluid acts similar to a cohesive solid. At this point applied pressure reaches the annular space above the screen portion and below the packer. This condition is known as a screen out.
When a screen out happens, high pressures are applied to the tubular that is above the screen portion and below the packer. There is a risk that the pressures generated while fracturing the formation at that point could be higher than the collapse strength of the tubular. One solution to this problem used in the past is to build the screen assembly out of heavier wall and/or higher material strength pipe including the base pipe portion that is under the screen. The problem with that approach is that it is expensive and when the well space is limited, the provision of thick wall pipe simply results in a decrease in the available inside diameter. That inside diameter constriction could impede the passage of tools through the screen for a subsequent operation and production from the well.
The present invention addresses this problem by allowing thicker wall blank pipe to be used adjacent to the packer and above the screen portion of the completion in conjunction with a lower rated tubular under the screen. To do this a transition piece is used at the top of the screen assembly that can be threaded into the thinner wall and/or smaller diameter and/or lower material strength pipe that underlies the screens and a larger diameter and/or thicker wall and/or higher material strength portion above the screen portion of the assembly. These and other aspects of the present invention will become more readily apparent from a review of the description of the preferred embodiment and the associated drawing that appears below while understanding that the full scope of the invention is measured by the claims at the end of the application.